More than one half of all printed products go in the mail. All items that go in the mail need addressing. Certain mailed items, such as post cards, folded and tabbed (or glued) flyers, and envelopes require the address affixed directly to them. It is also usual to print static messages and graphics on these items.
The current procedure in the direct-mail industry and prevalent for the last 25 years is to print the items on a traditional printing press and then put them on a subsequent addressing process that has a feeder and addressing capabilities. For the last 20 years the most common form of addressing has been inkjet printers attached to a material transport tables with material feeders. Companies such as MCS of Gaithersburg, Md., Secap of Conshohocken, Pa., Kirk-Rudy, Inc. of Woodstock, Ga., and Bryce Corporation of Memphis, Tenn., to name but a few suppliers/manufacturers, have offered such stand-alone printing and addressing systems for years. However, the two stages of first printing the items and then moving them to different equipment are very inefficient.
In the last 15 years there has been a dramatic increase in full-color, fully variable printing, mostly employing electronic printing with toner or inkjet. A typical and successful product is IGEN available from Xerox Corporation. This machine produces photographic printing that is fully variable. There have also been recent introductions of full-color inkjet presses. However, these printing processes are not yet as fast, as cheap or as prevalent as traditional printing presses utilizing offset techniques with, for example, printing plates.
Unlike traditional printing where each image is fixed by what is contained on the plate, with inkjet every image is unique. It is desirable to provide a technique that allows for the addition of variable information the traditional printing presses. One approach to providing such variable information is to locate a traditional mail table in line with a sheet-fed press so that the appropriate information can be added at this station (located, for example, upstream of the press). However, such an inline configuration requires a substantial increase in floor-space at the work area, and many extra components are required to fetch and accurately register the fed sheets with respect to the printing press.
It is recognized that inkjet print engine can make any location on the medium different from image to image. There are several patents that reveal new inventions by applying inkjet prior to a plate section in lithographic printing. For example, U.S. Pat. No. 4,833,486 applies inkjet printing to modify the ink receptor capabilities of the plate. Related patents make the image plate more oleophilic meaning “ink loving” or “oil loving” and hydrophobic (or ink-phobic) meaning “water shedding”. This use of inkjet on the plate is only to modify or condition the paper substrate to better receive ink from the plate, however, none of these patents contemplate making the image variable from impression to impression.